add a directory prefix to release-tar-file

Do not package tar file such that the sources are unpacked into the
current working directory. Use a directory prefix instead on creating
the tar file.

Fixes: #19066

Author: jklippel

Makefile

@@ -646,7 +646,10 @@ release-sources: | $(DIST_DIRS)
 	echo $(VERSION) > $(STORED_VERSION_FILE)
 # bsdtar needs a ^ to prevent matching subdirectories
 	$(eval EXCL := --exclude=$(shell tar --help | grep -q bsdtar && echo "^")./)
-	tar $(addprefix $(EXCL),$(TAR_EXCLUDES)) -czf $(DIST)/release/gitea-src-$(VERSION).tar.gz .
+# use transform to a add a release-folder prefix; in bsdtar the transform parameter equivalent is -s
+	$(eval TRANSFORM := $(shell tar --help| grep -q bsdtar || echo "--transform 's|^./|gitea-src-$(VERSION)/|'"))
+	$(eval TRANSFORM := $(shell tar --help| grep -q bsdtar && echo "-s '/^./gitea-src-$(VERSION)/'"))
+	tar $(addprefix $(EXCL),$(TAR_EXCLUDES)) $(TRANSFORM) -czf $(DIST)/release/gitea-src-$(VERSION).tar.gz .
 	rm -f $(STORED_VERSION_FILE)
 
 .PHONY: release-docs